Preparation and utilization of a sub-5 nm PbO2 colloid as an excellent co-catalyst for Pt-based catalysts toward ethanol electro-oxidation

Abstract

In order to improve the utilization and performance of Pt-based catalysts used in direct ethanol fuel cells, a commercial Pt black catalyst was modified by PbO₂ nanoparticles with a mean size of 4.59 nm. Electrocatalytic tests demonstrate that the as-prepared Pt black–PbO₂ hybrid catalyst possesses a much higher catalytic activity and longer durability than commercial Pt black for ethanol electro-oxidation. Specifically, the Pt black–PbO₂ hybrid showed an onset potential that was about 98 mV less positive, together with a peak current density 4 times higher than that observed for the commercial Pt black catalyst in the cyclic voltammetry tests. The ratio of current densities per unit Pt mass on the Pt black–PbO₂ and Pt black catalysts is 35.5 : 1 for the long-term (2 hours) chronoamperometric experiments measured at −0.4 V (vs. SCE). The in situ FTIR spectroscopic studies reveal that the Pt black–PbO₂ (4 : 1) catalyst exhibits excellent activity for breaking the C–C bond of ethanol, which is 3.21 times higher than that of the Pt black catalyst at 0 V (vs. SCE).